View Full Version : a question for the electrical gurus

10-18-2011, 08:05 AM
Right now I have headlights with the LED strip in them, and I currently have them wired so that the LEDs turn on as DRLs like in the newer Audi's.

My question is, how hard would it be to set up the LEDs to turn off on a per side basis if the turn signals were on like the newer Audi's do?

10-18-2011, 09:25 AM
Not sure how hard it would be, but quite a few people disable that on the new Audis. In ROW cars, they don't do that, only in north American cars to they wink.

10-18-2011, 10:24 AM
Ooh, this type of question is the type I am most interested in. I am currently doing a little research to see if there is a simple way to get this done. FYI: it tentatively involves 80's Mercury Grand Marquis parts. Won't be able to look into it further until this evening, though.

10-18-2011, 07:10 PM
Alrighty, I have a solution.


Taking inspiration from the turning lights (aka "Cornering Lights", aka "Ditch Lights") from the early 80's Mercury Grand Marquis and Lincoln Continental, this solution uses a relay that *interrupts* the 12V+ DRL signal from reaching the LED strip, but only whilst the turn signal is flashing on that particular side. Each front LED strip (Right and Left) would need it's own relay. The capacitor value is the variable and would be adjusted based on how quickly you want the LED strip to resume operation after the turn signal is canceled. Of course that time would need to be a minimum of 1 "flash", but it is probably beneficial to give it a little bit of extra delay. The diodes are only powering the relay (~150ma), not the lamp itself, so no worries about load on the components.

This homemade circuit would be the cheap and fun $10 solution. A more tailored solution would be a ready-made "Time-Delay Relay" with adjustable on and off delays, but would be considerably more expensive. Probably more like a $50 solution

I hope this was what you were after.

*Note* - I have not personally built or tested this circuit. This is what I have come up with based on some quick research and would be where I would start with this project. Informational only, at your own risk, if you blow your stuff up, etc, etc. Be safe out there.

10-19-2011, 12:33 AM
hmmmm, I wonder exactly what size capacitor to get. On the new cars, the LEDs don't go on/off as the actual turn signal bulbs themselves go on/off so you'd need one big enough to stay off while the bulb was in between flashes. I guess I'd need to time the blinks and go from there.

10-19-2011, 05:33 AM
Indeed. Now remember, the RC circuit is only controlling the small load of the relay, not the LED lamps directly. So all the cap has to do is keep the relay energized during the off-cycle of the flash - and probably a little longer. Again, the easy way is to pay the bucks for a fully adjustable purpose-made timer relay, but there's no fun in that.

Something I didn't mention: if you wanted to add some sort of "cornering lights" (ditch lights) to come *on* during the turn, you would just connect them to the "87" terminal. Those type of lights can help you with not inadvertently running into curbs or driveway drop offs, etc. I haven't a clue where or how'd you mount the actual lamp though. Just a thought.